(1) Field of the Invention
The present invention concerns a protective screen for a visual display device with a cathode ray tube having a display surface and a body structure for the cathode ray tube, comprising a filter layer which is operative for protection purposes.
(2) Description of the Prior Art
Cathode ray tubes of more modern display units have levels of electrostatic and electromagnetic fields and a level of other radiations, which are generally considered not to be harmful. In order to lower the levels of the above-mentioned fields and residual radiations, it may be appropriate or it may be required by some health regulations to dispose in front of the display screen a protective screen which performs a filter function in regard to the electrostatic and electromagnetic fields and the residual radiation emitted by the cathode ray tube.
A screen of the above-defined type is known, which is permanently mounted between the body structure and the display surface of the cathode ray tube. That known construction is expensive since it adds the cost of the screen to the cost of the display unit, even when the screen is not strictly necessary. In addition the known construction does not permit the protective screen to be removed from the display screen when that might be required for cleaning the screen and to provide a better view of the images on the cathode ray tube.